In the construction industry, the problem of noise transmission from one room to another within a building has become significant with the advent of large office buildings and huge apartment complexes. It is important that the floors, walls, and ceilings of offices or apartments be sound-insulated so that speech, music, or like sounds from one room are not heard in an adjoining room. Good sound insulation is particularly important in flooring since the flooring must not only resist transmission of airborne sounds such as music or speech, but must also insulate against impact-produced sounds resulting from walking, moving of furniture, and the like.
Sound-insulating flooring which has previously been used, or which is in present use, is generally either difficult to install, yields poor sound insulating qualities or is quite expensive. To prepare one such floor, a thick, wet mixture of Portland cement with sand is poured in the usual manner onto a subfloor, this well-known cement thereafter being troweled and finished to provide a smooth flooring. Since the horizontal dimensions of a floor in an office or apartment are fixed by the walls, shrinkage during setting of a poured Portland cement floor results in cracks in the floor which can seriously reduce the effectiveness of the floor as a sound barrier. Since the concrete mixture is quite thick and pasty, considerable effort and time and hence expense, is involved in pouring and finishing a floor of this type.
Other sound-insulating floors involve the installation of pre-formed sheets of particle board or of gypsum-type sheetrock. Considerable effort is required in cutting such pre-formed sheets to the exact size of the floor so as to avoid cracks or fissures between abutting sheets or between the edges of the sheets and the walls. Since the sheets must be cut to size, a considerable waste of material results.
To form a good acoustic barrier, an acoustic flooring layer should be free of cracks and should extend into abutment with the walls. In addition, the flooring should be capable of having nails pounded through it without chipping, as when carpeting is laid over the flooring. For good resistance to sound transmission, the flooring should be generally quite dense. Further, at least the upper surface of the flooring should be hard so as to resist denting or other deforming which may be caused by accidental dropping of heavy objects on the floor or by applying continuous, concentrated weight to the floor as by the feet of a waterbed or refrigerator or other heavy object. From an economic standpoint, the floor should be quickly and easily laid and finished.
The subfloor, or underlayment, upon which acoustic flooring is installed often is plywood, which may delaminate when soaked with water. Moreover, the walls of offices and apartment complexes quite commonly are of a gypsum-type wallboard which may be damaged when soaked with water. To avoid water damage to the subfloor and wallboard, some means of controlling water seepage is required to prevent water damage when an acoustic floor is prepared from a water-containing mixture such as that described above.
A flooring which can be easily poured and finished with a minimum expenditure of time and without waste of material, which would avoid water damage to subflooring and wallboards, which would be highly resistant to cracking or chipping in use, which would extend completely to the walls and be anchored securely to the subflooring, and which would offer high resistance to sound transmission, is much to be desired.